User Manual

A-3
Soft Foot Evaluation
The Soft Foot evaluation provides you with a sense of severity without
showing numbers. Numbers are not used because,
most of the time, they are
mistaken for the value of the shims
(totally wrong). When the numbers are cal-
culated, they are compared against the tolerance (usually 0.5 mils/inch). If
a particular foot is below the tolerance, it is labeled OK. If the number is
between one and two times the tolerance, it is labeled with a single X. If the
number is between two and three times the tolerance, it is labeled as XX.
If the number is greater than three times the tolerance, it is labeled as XXX
(the more X’s, the greater the severity).
The tolerance can be changed in
UltraMgr and downloaded to the analyzer
.
The number is evaluated by taking the horizontal and vertical movement
on each target and calculating the total movement on each target. The
largest movement of the two is then divided by the distance between the
heads (dimension C) to determine the angle of deflection caused by loos-
ening a hold-down bolt. This angle is compared to the tolerance for final
evaluation for that foot.
The advantage of this method is that it uses a combination of horizontal and
vertical movements on the target to determine the problem feet. Experi-
ence has shown that approximately 20% of the soft foot conditions cause a
horizontal move
because of a severely bent foot .
FDI Evaluation
The Frame Distortion Index provides you with a sense of severity with
numbers
.
Caution!
Do not mistake these numbers for shim values.
When the numbers are calculated, they are compared against the tolerance
(
usually excellent <2 mils and acceptable <3 mils). If a particular foot is in
the excellent range, the number is plain. If the foot is acceptable, it will have
a clear box around the number. If the foot is out-of-tolerance, it will have a
solid box around the number. The higher the number, the greater the
severity.
The tolerance values can be changed in UltraMgr and downloaded to the
analyzer
.